The present invention relates to the field of the non-intrusive analysis of the electricity consumption of a residential, commercial or industrial site i.e., not requiring the introduction of sensors associated with each one of the devices to be monitored nor the switching off of the power supply of the installation. This analysis more particularly makes it possible to identify the key leverages of power saving.
In the state of the art various solutions are known, which consist in acquiring information on the waveform factors of the current and/or voltage upstream from the site, and in deducing information on the individual consumption of each one of the electrical devices.
One family of solutions consists in observing the time variations of the load curve and in identifying signatures compared with reference signatures saved for the main devices.
In particular, the European patent application EP2000780 describes a method for detecting and estimating the consumption of electrical uses of a subscriber's facilities, characterized in that it consists at least in:                establishing the curve of the general electricity consumption of the subscriber's facilities, with the step of establishing the curve of the general consumption of the subscriber's facilities including at least: sampling the consumption of the effluent consumed by the subscriber's devices, with said sampling being carried out downstream from the consumption effluent meter connected to the general network connection;        identifying, through a segmentation of the curve of the general consumption of the subscriber's facilities and through a tracking of the transient-state power consumption events, the electrical uses and estimating the corresponding consumption thereof.        
The international patent application WO 2010106253 also knows, which describes a method for analyzing the electricity consumption of a plurality of electrical devices operating on a consumption site, by filtering a load curve representing the electricity consumption of the devices vs time, characterized in that it comprises the following steps:                prior to the actual filtering of the load curve:        scanning and saving the load curve, in order to obtain a digitized load curve vs time periods;        defining a set of class of devices, with each class being defined by similar power variation cycles;        defining, for each class of devices, a load curve filtering algorithm dedicated to said device class, with said algorithm being adapted to retrieve power variation cycles of the digitized load curve, and allocate it to said class of devices;        then during the filtering proper of the digitized curveload, successively using the filtering algorithms dedicated to each class of devices, to identify and gather, from the digitized curveload, variations in the cycles of the power consumed by the electrical devices.        
A second family of solutions consists in taking into account not the time variation of the power measured upstream from the installation, but in taking into account the waveform of the current consumed by each one of the devices.
In particular, the international patent application WO2011012840 relates to a method for identifying the operation of an electrical device, for example an induction motor. The method comprises identifying the operation of an electrical device when a path traced by effective power values with respect to corresponding virtual power values during a particular period comprises one or more substantially circular arcs. The effective power values are associated with the total effective power supplied to one or more electrical devices over time, and the virtual power values are associated with the total virtual power supplied to one or more electrical devices over time. The invention also relates to an associated method for identifying the operation of a specified type of device, wherein the operation of said specified type of device depends on the supply of at least one source of energy, such as electricity, natural gas, or water. The invention also relates to computer programs, computer-readable media and corresponding computer program products and devices.
The European Patent 1296147 is also known, which describes a method for estimating the individual electricity consumption of a plurality electrical devices consisting in:                creating a model to estimate the electrical power consumption of each one of the electrical devices from the relationship between the data on full load current fundamental and higher-order harmonics and the voltage phase differences thereof from the full load current and the voltage obtained from combinations of various operating conditions of a plurality of electrical devices and the electrical consumption used to obtain said data        and get the electricity consumption of operating individual devices using said model to estimate the consumption of each device from said fundamental and higher-order harmonics of said full load current and said voltage phase differences thereof obtained from said full load current and voltage measured in the vicinity of a service entrance.        
The processes consisting in observing the time variations of the load curve and identifying signatures compared with reference signatures saved for the main devices are not adapted to the analysis of sites with a large number of devices. As a matter of fact, the frequency of acquisitions is of the order of one second. When several devices stop or start with a small time lag, lower than the frequency of acquisition, a masking phenomenon occurs that prevents a relevant recognition of devices involved.
Besides, the method takes into account the transients only (on/off), and does not enable one to take into account the devices in continuous operation.
These problems have led to develop the second family of solutions based on the analysis of waveforms.
The technical problem with these methods is the reliability of the processing. As a matter of fact, these methods are based on the characterization of a device by a signature saved in a particular situation. When the device is used on a site, this signature is slightly disturbed, more particularly by the quality of the supply voltage. It is therefore necessary to provide a margin of error to enable the effective detection of the devices. The margin of error leads, however, to a risk of confusion between different devices, but each one being characterized by close signatures.
This problem prohibits the possibility of a universal database and requires a modeling for each site.